import re
def change_char(s, p, r): return s[:p] + r + s[p + 1:]

def parse_phone_number(text): numbers = re.findall(r"\d+", text)

if numbers is None:
    return None

res = re.search(r"([87])([7])\d{9}|([7])\d{9}", ''.join(numbers))

if res is None:
    return None

phone_number = res.group()

if phone_number[0] == "8":
    phone_number = change_char(phone_number, 0, "7")

if len(phone_number) == 10:
    phone_number = "7{0}".format(phone_number)

return int(phone_number)